1. Field of the Invention
The present invention relates to a connecting apparatus and method for providing electrical connection between respective electrodes of two high-frequency circuit boards, and in particular, to a connecting apparatus and method for providing electrical connection between respective electrodes of two high-frequency circuit boards for use in bands of frequencies such as microwave frequencies, sub-millimeter wave frequencies, millimeter wave frequencies or the like.
2. Description of the Related Art
FIG. 7 is an exploded perspective view showing a configuration of a connecting apparatus of a prior art for providing electrical connection between respective electrodes 11 and 21 of two high-frequency circuit boards 10 and 20. FIG. 8 is a cross sectional view taken along the line G-Gxe2x80x2 of FIG. 7. FIG. 9 is a cross sectional view taken along the line H-Hxe2x80x2 of FIG. 8.
In the prior art shown in FIGS. 7 to 9, the electrodes 11 of one high-frequency circuit board 10 are brought into contact with electrode connecting parts 21t (generally called pads) of the electrodes 21 formed on another high-frequency circuit board 20 through contact probes 90 (generally called pogo pins) which are soldered to electrode connecting parts 11t of the electrodes 11 or fitted into through holes 11h of the electrode connecting parts 11t (generally called pads) by means of inserting with pressing or the like, and this leads to that the electrodes 11 and 21 are made to be electrically connected with each other. In the prior art, each of the high-frequency circuit boards 10 and 20 is, for example, made of a hard dielectric board or an FPC (flexible printed wiring board).
However, a mismatch between characteristic impedances occurs in the contact probes 90 when the electrodes 11 and 21 of the two high-frequency circuit boards 10 and 20 are electrically connected with each other by means of the contact probes 90 which are so-called pogo pins. In this case, there are the following problems. Namely, not only point contacts but also repeated contacting would cause wearing away of the tips of the contact probes 90, the contact probes 90 and the electrode connecting parts 11t and 21t, and this leads to deterioration in DC (direct current) characteristics and high-frequency characteristics at an early stage, which results in unsatisfactory longevity.
Moreover, each center pin is singly replaceable in the contact probe 90, however, the whole high-frequency circuit boards 10 and 20 must be replaced with another ones in the electrode connecting parts 11t and 21t. Therefore, when expensive parts are mounted on the circuit boards 10 and 20, the circuit boards 10 and 20 become expensive, and then, the repairing cost become higher.
Furthermore, structural design is limited due to the influence of the size and shape of the contact probe 90. That is, the following problems exist:
(1) the connecting electrodes cannot be arranged with a smaller pitch due to a diameter of the contact probe 90 and the through holes 11h formed in the high-frequency circuit board 10; and
(2) an arrangement of components cannot be provided on a back surface of the high-frequency circuit board 10 since the contact probes 90 must be fitted in and pass through the high-frequency circuit board 10, and an unnecessary space must be provided since the contact probes 90 projects through the back surface of the high-frequency circuit board 10.
It is an essential object of the present invention to solve the above-mentioned problems and to provide an apparatus and a method for connecting high-frequency circuit boards, which achieve less deterioration in high-frequency characteristics, a simpler structure, a smaller size, a lighter weight, a longer life and more inexpensiveness as compared with those of the prior art.
In order to achieve the aforementioned objective, according to one aspect of the present invention, there is provided an apparatus for connecting high-frequency circuit boards, for providing electrical connection between respective electrodes of two high-frequency circuit boards, comprising:
an electrode connecting member including a bar-shaped member having a predetermined sectional shape, and including connecting electrode means formed on a part of an outer periphery of the bar-shaped member,
wherein the connecting electrode means is located so as to provide inter-connection between the respective electrodes of the two high-frequency circuit boards through the connecting electrode means and to be sandwiched between the respective electrodes thereof.
In the above-mentioned apparatus, the connecting electrode means preferably comprises a plurality of electrode lines formed so as to be spaced at a predetermined interval on the outer periphery of the bar-shaped member. Alternatively, in the above-mentioned apparatus, the connecting electrode means preferably comprises a plurality of sets of connecting electrodes, respective sets of connecting electrodes are formed on the outer periphery of the bar-shaped member so as to be spaced at a predetermined first interval corresponding to an interval between the respective electrodes of each of the two high-frequency circuit boards, and each set of connecting electrodes is formed of a plurality of electrode lines which are spaced at a predetermined second interval smaller than the first interval on the outer periphery of the bar-shaped member. Further alternatively, in the above-mentioned apparatus, the connecting electrode means preferably comprises a plurality of planer solid electrodes which are formed on the outer periphery of the bar-shaped member so as to be spaced at a predetermined first interval corresponding to an interval between the respective electrodes of each of the two high-frequency circuit boards.
The above-mentioned apparatus preferably further comprises a positioning member for positioning the electrode connecting member between the two high-frequency circuit boards so that the connecting electrode means provides inter-connection between the respective electrodes of the two high-frequency circuit boards so as to be sandwiched between the respective electrodes thereof.
In the above-mentioned apparatus, the plurality of electrode lines is preferably arranged to comprise a structure of coplanar line.
According to another aspect of the present invention, there is provided a method for connecting high-frequency circuit boards, for providing electrical connection between respective electrodes of two high-frequency circuit boards, the method including the step of locating connecting electrode means so as to provide inter-connection between the respective electrodes of the two high-frequency circuit boards through the connecting electrode means and to be sandwiched between the respective electrodes thereof, by means of an electrode connecting member including a bar-shaped member having a predetermined sectional shape, and including the connecting electrode means formed on a part of an outer periphery of the bar-shaped member.
In the above-mentioned method, the connecting electrode means preferably comprises a plurality of electrode lines formed so as to be spaced at a predetermined interval on the outer periphery of the bar-shaped member. Alternatively, in the above-mentioned method, the connecting electrode means preferably comprises a plurality of sets of connecting electrodes, respective sets of connecting electrodes are formed on the outer periphery of the bar-shaped member so as to be spaced at a predetermined first interval corresponding to an interval between the respective electrodes of each of the two high-frequency circuit boards, and each set of connecting electrodes is formed of a plurality of electrode lines which are spaced at a predetermined second interval smaller than the first interval on the outer periphery of the bar-shaped member. Further alternatively, in the above-mentioned method, the connecting electrode means preferably comprises a plurality of planer solid electrodes which are formed on the outer periphery of the bar-shaped member so as to be spaced at a predetermined first interval corresponding to an interval between the respective electrodes of each of the two high-frequency circuit boards.
The above-mentioned method preferably further includes positioning the electrode connecting member between the two high-frequency circuit boards, by means of a positioning member.